This review highlights several key findings about programs designed to increase learning for children and youth through longer school days, longer school years, and programs that expand learning opportunities during and into the out-of-school time hours. We reiterate these findings below:

While the evidence base for ESD and ESY models is quite thin due to the lack of well-designed, rigorous studies focusing on their effectiveness, the available evidence suggests that schools implementing longer school days and longer school years can be effective in raising academic performance, as indicated by test scores.

However, more research is needed focusing on the unique effect of the longer school day or longer school year over and above other school features and reform efforts. A better understanding of the circumstances under which extended learning time is beneficial is critical, primarily because the findings in the literature indicate that simply adding time is insufficient. A number of possibilities exist for why more time is helpful. It could be that students need more time to engage actively in academic activities, in which case, one would want to avoid ELT approaches that focus primarily on teacher instruction and downplay interactive learning. It could also be that more time in the classroom provides greater opportunities for teachers and students to interact, allowing teachers more opportunity to understand and respond appropriately to a greater number of students in their classroom. Understanding the pathways through which the additional time might be useful will be helpful to educators and policymakers interested in implementing these approaches.

Because it is difficult to know if findings result from "selection" effects associated with the characteristics of participants who voluntarily choose to attend a certain school or participate in a certain program or from the program itself, more well-implemented, randomized experimental studies are needed.

Evaluations of extended learning opportunities suggest that they are more effective in improving psychological indicators of educational adjustment that are precursors to educational achievement, such as educational expectations. Although some ELO programs have been found to be effective in improving academic achievement and educational attainment outcomes, most of the programs that targeted and measured these outcomes had no impact.

Program implementation and quality matters. Schools and programs that are well-implemented, that attract strong participation, and that are of high quality tend to have positive effects, while those that suffer from poor implementation have no effects or even negative effects on children and youth.

Although very few of the studies included in this review provided information on effect sizes, among those studies that did, effects for significant findings ranged mostly from small to moderate. Based on information about percentage-point differences found between students participating in extended-learning schools or programs and comparison students, some models had effects that were medium in size.xiv

References

xiv Because measures of the strength of effects (effect sizes) were not commonly or consistently reported across the set of evaluations, this review focuses largely on the patterning and consistency of outcomes. However, the issue of magnitude of effects is addressed to the extent possible in this report. Cohen (1988) offered guidance for interpreting effect sizes in order to estimate their practical significance. When comparing two groups, he recommended that an effect size of 0.20 should be considered "small," an effect size of 0.50 be considered "medium," and an effect size of 0.80 be considered "large." According to Cohen, these guidelines are somewhat arbitrary and are, therefore, most useful when no other standard is available for understanding the magnitude of an effect. Over the past decade, further work has explored the issue of interpretation of effect sizes in education research and in social experiments more broadly. Bloom and colleagues (2008) articulate the importance of assessing the size of an effect within the context of other key pieces of information, including the effect sizes found for similar interventions, the effect sizes found on outcomes of interest, and the normative range of expectations, such as the amount of growth that might normally be observed in test scores over a certain period of time. Konstantopoulos and Hedges (2005) also stress the importance of evaluating school-level effects within the normative distribution that is expected.